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More than 30 years after Thomas Lovejoycoined the term "biological diversity" and made projections about global extinction rates, the chairman of the Heinz Center for Biodiversity is still trying to get the world's attention about the dwindling number of animals inhabiting the earth.

The first projection of species extinctions came in 1980 — a prediction I made in a report for then president Jimmy Carter. It concluded that the pace at which we were losing tropical forests to logging and development would cause the extinction of 15 to 20 percent of all species by 2000. The calculation was not far off. Today's Red List of Threatened Species, from the International Union for Conservation of Nature, estimates that 13 percent of bird, 25 percent of mammal and 41 percent of amphibian species face possible extinction.

Lovejoy highlights some of nature's most visible creatures: big cats like lions and tigers. He says scientists have a term for animals most of us never think of as endangered: the "living dead." At the current rate of extinction, he writes, these wild creatures will no longer live in the wild and will be confined to zoos and wildlife areas a century from now.

A Minnesota scientist, meanwhile, is playing a prominent role in efforts to avoid that outcome.

Dr. Tara Harris directs the Minnesota Zoo's conservation work. In addition to coordinating tiger conservation with other zoos around the country, she's spearheading initiatives closer to home to save creatures that might not be as visible as the big cats.